//1.通过push的方法
let array = [1, 2, 3, 4, 5]
array.push(6)
console.log(array) //[1, 2, 3, 4, 5 , 6]

//2.array[array.length]
array[array.length] = 100
console.log(array) //[1,2,3,4,5,100]

//3.arr.splice(arr.length,0,"增加的项")
array.splice(array.length, 0, "增加的项")
console.log(array) //[1,2,3,4,5,100,"增加的项"]
